The present invention relates in general to an improved technique for the mounting of millimeter microwave control and/or signal components into an RF transmission medium. More particularly, the present invention relates to an improved mounting system and associated method of manufacture particularly applicable at higher millimeter frequencies wherein microwave components are of substantially reduced size.
At the present time and in particular at lower millimeter frequencies, packaged devices are conventionally used and are readily mounted into a transmission medium such as into a length of waveguide using posts or mechanical transition pieces. At these lower frequencies this form of mounting is satisfactory and provides minimal performance degradation. However, at higher millimeter frequencies when the component dimensions are substantially reduced, it has been found that existing techniques are undesirable and in many instances are outright unworkable. These mounting techniques are undesirable because they cause degradation of electrical and mechanical parameters and are costly to implement. For example, not only is there the difficulty in handling smaller components, but there is also the ever present problem regarding undesirable electrical effects at these junction connecting points thus affecting the circuit operation.
By way of example, a high power limiter may be provided by placing a semi-conductor window control element across a waveguide. Fabricated into one surface of this window is a matrix of p-i-n diodes. In the unbiased state, these diodes appear as a shunt capacitance across the waveguide. In the biased conducting state, the diodes produce a large admittance across the path of the millimeter wave. These semi-conductor window control elements may be mounted into a standard waveguide by several means including by direct soldering or by using a separately attached gold membrane peripheral frame. The gold membrane is provided with an opening to expose the window control element (diode array), and is bonded by soldering to the periphery of the silicon window chip. The window is placed into the waveguide (or a section of waveguide) and the gold membrane is clamped between two waveguide flanges. These techniques require at the very least some form of soldering or welding for affixing the semi-conductor chip to the frame-like membrane. As indicated previously, particularly at higher millimeter frequencies there is extreme difficulty in handling relatively small semi-conductor circuits and in providing effective connection to the gold membrane. As a result, undesirable electrical affects occur at these solder or weld points thus affecting the overall operability of the circuit.